The goal of this NIH Phase I SBIR proposal is to develop and validate a new method to monitor the symptomatic toxicities and health-related quality of life of cancer patients who are undergoing and have undergone radiation therapy during the course of their treatment. The proposal is built around expertise in mobile application development (Vivonics Inc.) and radiation oncology (Dr. TJ Fitzgerald of the University of Massachusetts Medical School). Phase I will allow this uniquely qualified team to develop, test, and validate the proposed mobile application that we call Symptomatic Toxicity Mobile Monitor (SympTMM). Improvements to both the quality and availability of cancer treatment has led to a marked increase in the number of patients surviving cancer, often times for a previously unimaginable number of years. In 2012, 64% of patients survived greater than 5 years, 40% greater than 10, and 15% greater than 20 after diagnosis (De Moor, Mariotto et al. 2013). The caveat is that while survivors are living longer, the volume of new cancer patients each year is steadily increasing. This trend is expected to continue over the coming decade, taxing our limited understanding of the longer-term impacts on the various treatments used today